Piezo-resistance effect in composite based on cross-linked polydimethylsiloxane and polyaniline: potential pressure sensor application

Composites that incorporate an electrically conducting filler, the hydrochloric polyaniline (PANI-Cl), into hydroxy-terminated polydimethylsiloxane (HO-PDMS) matrix were evaluated for DC electrical, mechanical, thermal, morphological and piezo-resistive properties. The main focus of the study was on the electrical–mechanical behavior of these composites in view of possible piezo-resistive sensor application. The percolation threshold of conductivity was determined to be around 11.5 wt% of PANI-Cl. Compression/expansion cyclic experiments showed that the filler content modified the stiffness, the magnitude of Mullins effect and the hysteresis behavior in elastomeric composites. The piezo-resistive response of composites differed depending on the sample composition and also, on the strain rate. Composites with concentration above the percolation threshold exhibited at least three-order change of its electrical resistance in a narrow interval of maximum 2% of deformation. The piezo-resistive sensitivity and the reproducibility of response suggested the possibility to use this material as a transducer in an electromechanical device.